Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-02-26
2001-03-27
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S395430, C370S469000
Reexamination Certificate
active
06208646
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ATM (Asynchronous Transfer Mode) transfer system of data packets for transferring low bit-rate and variable-length data packets such as voice packets making use of an ATM transfer network.
Conventionally, data packets such as voice packets are transferred on ATM cells by way of a VC (Virtual Channel) established between a packet transmitter and a packet receiver when the data packets are transmitted from a terminal to a terminal.
When data packets are to be transmitted from a terminal to a plurality of terminals for a broadcast communication, data packets are duplicated at an ATM layer. An example of the broadcast communication method is disclosed in a Japanese patent application laid open as a Provisional Publication No. 349737/'92, wherein each of ATM cells input to an ATM exchange is duplicated into N ATM cells when the data packets transmitted from a packet transmitter are to be transferred to N (N being an integer more than one) packet receivers regardless of data packets loaded on the ATM cells. By rewriting header information of every duplicated ATM cell with header information indicating each corresponding destination by the ATM exchange at the ATM layer, each of the plurality of ATM cells having the same data is output to be delivered to each of the plurality of packet receivers.
In conventional ATM transfer systems as above described, each one data packet is transmitted loaded on one ATM cell, using ATM circuits with low efficiency. It is because a part of the ATM cell is left useless occupying communication capacity of the ATM network in vain when a data packet such as a voice packet is loaded on the ATM cell having a fixed data length, since the low bit-rate and variable-length coding of the voice packet has been remarkably progressed along with progress of the voice data compression technique. Furthermore, this inefficiency accompanying the low bit-rate and variable-length coding of the voice packet is also duplicated in the above broadcast method wherein the same number of ATM cells to the number of destinations are all duplicated at the ATM layer.
For improving the transfer efficiency of the ATM network, multi-loading of the ATM cell is proposed recently, wherein data packets having different destinations, designated by AAL (ATM Adaptation Layer) header information added to each of the data packets, are multi-loaded on the same ATM cell, which is duplicated at a transmitter-side exchange to be sent out to different receiver-side exchanges. multi-loading refers to the process of multiplexing and packing the data packets on the ATM cell. thus improving efficiency by utilizing more of the communication channel.
However, when the multi-loaded ATM cell is duplicated at the ATM layer, in such a way as performed in the above broadcast method, according to fixed destinations registered when the call is established, there is still left certain inefficiency. This is because data packets such as voice packets may not be generated regularly, and ATM cells having no concerning data packet may be duplicated and transferred in vain to some receiver-side exchanges when data packets concerning to the receiver-side exchanges are not generated.
SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to provide an ATM transfer system of data packets wherein transmission efficiency is improved by eliminating useless duplication of the ATM cells occupying the ATM network capacity in vain.
In order to achieve the object, in an ATM transfer system of data packets according to the invention having an ATM network including a transmitter-side exchange connected to a transmitter-side network terminal, and more than one receiver-side exchange:
the transmitter-side exchange comprises an AAL (ATM Adaptation Layer) processing circuit for generating duplicated ATM cells each to be sent to each of certain of said more than one receiver-side exchange by duplicating an original ATM cell transmitted from the transmitter-side network terminal when cell header information of the original ATM cell indicates that the original ATM cell is multi-loaded of data packets destined to different packet receivers, each of said certain of said more than one receiver-side exchange accommodating at least one of the different packet receivers designated by AAL header information accompanying each of the data packets;
one of said more than one receiver-side exchange connected to more than one receiver-side network terminal comprises another AAL processing circuit for generating new ATM cells each to be delivered to each of certain of said more than one receiver-side network terminal when a duplicated ATM cell arrives having cell header information indicating that the duplicated ATM cell is multi-loaded with data packets destined to different packet receivers, each of the new ATM cells being loaded with at least one of the data packets multi-loaded in the duplicated ATM cell, each of said at least one of the data packets being destined to at least one packet receiver designated by, AAL leader information accompanying said at least one of the data packets and connected to corresponding each of said certain of said more than one receiver-side network terminal; and
one of said more than one receiver-side network terminal connected to more than one packet receiver accommodated in one of said more than one receiver-side exchanges comprises still another AAL processing circuit for generating data packets each to be sent to each of certain of said more than one packet receiver by duplicating a data packet loaded on a new ATM cell delivered from the receiver-side exchange when AAL header information accompanying the data packet indicates that the data packet is destined to said certain of said more than one packet receiver.
REFERENCES:
patent: 5701300 (1997-12-01), Jeon et al.
patent: 5907536 (1999-08-01), Foglar
patent: 5940393 (1999-08-01), Duree et al.
patent: 827305 (1998-03-01), None
patent: 4-349737 (1992-12-01), None
patent: 9738550 (1997-10-01), None
patent: 9818286 (1998-04-01), None
“AMulticast Single-Queue Switch with a Vovel Copy Mechanism” by Hashemi et al. IEEE, pp. 800-807, Aug.,1998.*
International Search Report issued in connection with the corresponding PCT application (Aug. 19, 1998).
Hsu Alpus H.
NEC Corporation
Ostrolenk Faber Gerb & Soffen, LLP
Qureshi Afsar M.
LandOfFree
ATM transfer system of data packets does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with ATM transfer system of data packets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ATM transfer system of data packets will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2479510